CN102857581A - Web service finding method based on balanced binary tree Chord network architecture - Google Patents

Abstract

The invention discloses a web service finding method based on balanced binary tree Chord network architecture, and the method is used for solving the corresponding service finding problem in a mixing mode and implementing a solution for semantic Web service finding through a provided Enhanced-AVLTree and Chord structure mixed architecture. A network model is divided into two layers; an upper layer is grouped by aiming at the classification of a semantic domain to which a service type belongs, and a corresponding service classification grouping node tree model is constructed by using Enhanced-AVLTree; a lower layer constructs resource publishing and implementation of the service of the classification by using the Chord structure, and the semantic domain to which a service belongs is quickly positioned under the condition of guaranteeing O(logn) by the Enhanced-AVLTree structure; a peer-to-peer (P2P) network is constructed in a manner of combining Enhanced-AVLTree and Chord, so that balance of a network load is facilitated, and the defect of non-uniform load of the conventional network is overcome; and due to the semantic Web, the query positioning result is relatively accurate.

Description

A kind of Web service discover method based on balanced binary tree Chord network configuration

Technical field

The present invention relates in particular to a kind of Web service discover method based on balanced binary tree Chord network configuration mainly towards the release quickly of extensive Semantic Web Services with pinpoint the problems.

Background technology

In service compute, Web service is a kind of concrete manifestation form and the function carrier of service concept, and it is a kind of having self adaptation, self-described, modularization and having the application program of good interoperability based on the Web environment.Web service has been played the part of more and more important role in fields such as ecommerce, enterprise's application integration as a kind of novel distributed component object model.Along with the increase of Web service number and kind in the Internet, how to carry out service discovery is one of Enterprise SOA SOA key issue to be solved easily and effectively.In recent years, Chinese scholars is thrown oneself into the Web service discover method of semantic-based one after another, by using the ontology in the semantic net (Semantic Web), the ability that the semantic reasoning technology improves service discovery, such method unanimously is known as the most promising service discovery method by current academia, this class methods overwhelming majority reaches automation and the accuracy of service discovery process take semantic Web service model OWL-S, WSMO and WSDL-S etc. as the basis in conjunction with technology such as ontology inference, semantic matches.

Traditional Web service discover method is realized by the centralized solution substantially, such as popular CS framework etc., the defectives such as but along with the increase of enriching constantly of quantity of service, such centralized solution will occur inevitably that server relies on, validity is low, single point failure and autgmentability are poor.When the registered set of magnanimity during to service register center, will inevitably cause the high load capacity running of service register center, in case and if the collapse of service register center Centroid, all Web services that are registered in this service centre all can't be found to utilize, and will cause immeasurable loss.Yet the appearance of P2P technology has broken through original traditional centralized network pattern, utilize distributed resource, realize certain function or support a system with the mode of disperseing, the P2P network has the characteristics such as distributivity, self-organization, extensibility, fail safe and interoperability.The P2P technology is through years of researches and development, produced the effective P2P network of many maturations, such as Napster, Gnutella, Chord, CAN, JXTA etc., all node status in the P2P network all are equality, each node both provided required service as server for other nodes, the service that can use other nodes to provide as client again, the risk of the server that the pattern of so reciprocity status is shared also greatly reduces the possibility of whole periods of network disruption.The height maximum differential of two subtrees of any node is one in the balanced binary tree (AVLTree), in balanced binary tree, search, insert and delete under average and worst case all is O(log n), by all nodes among the AVLTree all being added the address (quoting or pointer) of pointing to root node, namely can initiate to seek from any point, can find the node of looking in this tree.Be called Enhanced-AVLTree by the AVLTree(after improving like this) also become a kind of P2P computation model of structural formula.

Summary of the invention

The defectives such as the efficiency bottle neck of finding for traditional centralized service, poor expandability, the present invention proposes a kind of semantic Web service finding method of P2P network configuration of mixing based on Enhanced-AVLTree and Chord, utilizes the advantages such as distributivity, extensibility, interoperability of P2P network to provide a kind of service discovery strategy process rapidly and efficiently for service requester.

In order to solve the problems of the technologies described above, technical scheme of the present invention is as follows:

A kind of Web service discover method based on balanced binary tree Chord network configuration comprises service networking process and service discovery process;

Described service networking process comprises the steps:

11) set initial condition, the node set G of group acquiescence is arranged in the network ₀, the node of any not service issue all belongs to this group, and first node that adds this group becomes the tree node T of this group ₀, described tree node T ₀Preserve the root node R of whole tree network ₀The address;

12) for the node P of new adding network _i, at first it is joined node set G ₀, described node P _iBy the following steps Web Services Publishing:

121) node P _iThe Web service w that at first wish is issued _iCorresponding semantic domain w _{I_}Category sends to the tree node T of this group ₀, tree node T ₀It is transmitted to root node R ₀

122) carry out the service type value key0 that Hash mapping obtains each tree node according to semantic domain, namely by computing semantic category w _{I_}The cryptographic Hash key0 of category _i, in network, find and semantic domain w according to the search rule of Enhanced-AVLTree tree _{I_}The semantic nearest tree node R of catogery _x

123) calculate tree node R _xCorresponding semantic domain R _{X_}Catogery and w _{I_}The semantic similarity Sim(R of catogery _{X_}Catogory, w _{I_}Catogory), if the similarity value, thinks then that both semantemes are similar greater than given threshold value, node P _iJoin tree node R as the link point _xAffiliated Chord ring is by corresponding Chord agreement, according to node P _iThe IP address computation go out respective nodes P _iCryptographic Hash to determine node P _iPosition in this Chord ring, and calculation services w _iThe corresponding service value of Query Information key1 _i, pass through key1 _iWith releasing news＜w of service _i, IP_w _iBe published to corresponding node P _xOn;

124) if step 123) calculate semantic dissimilar, node P _iOneself become tree node R _i, set up new Chord ring G _i, node R _iUnique identification in Enhanced-AVLTree tree network is according to semantic domain w _{I_}Catogory carries out Hash mapping and obtains, along with node R _iAdding, the rule of the network based balanced tree of whole Enhanced-AVLTree is upgraded;

During 13) for the new service of node issue that joins in certain ring, at first information on services is sent to the tree node of this node place ring, then according to step 121) ~ 124) issue;

Described service discovery process comprises the steps:

14) service requesting node is initiated service-seeking request query, through obtaining carrying out the query requests query_category of semantic matches after the semantic processes;

15) query requests query_category is transmitted to the tree node R that the affiliated ring of node is sent in request _iIf query requests just comes from this tree node, then can omit this step;

16) tree node R _iAfter receiving query requests query_category, will process query requests, concrete steps are as follows:

161) query requests query_category is mated with the historical query buffer memory of this locality, if hit, then directly the result is returned to request forwarding person, otherwise enter step 162);

The semantic similarity of the semantic domain that 162) calculating query requests query_category is corresponding with tree node, if semantic similar, then search the semantic similar Web service to query requests query_category according to the Chord agreement in the ring under own, result queries is returned to the request promoter, upgrade simultaneously local historical query buffer memory, otherwise enter step 163);

163) query requests query_category is transmitted to the meeting point the most similar to query requests query_category semanteme, according to the rule of Enhanced-AVLTree, query requests query_category is transmitted to root node R ₀, the tree node R that then meets to semantic similarity according to the rule searching of binary search tree _x, then at tree node R _xSearch the cryptographic Hash key1 of the corresponding inquiry service information of query requests query_category according to the Chord agreement in the affiliated ring _q, find corresponding service and release news and send to inquiry and initiate node, if exceed the restriction jumping figure that sets in the ring, then inquire about unsuccessfully, return equally query failure message.

Beneficial effect of the present invention is: the mode by a kind of mixing solves corresponding service discovery problem, utilizes the mixed architecture of Enhanced-AVLTree above-mentioned and Chord structure to realize the solution of semantic Web service finding.This network model is divided into two-layer, the upper strata is to divide into groups for the classification of semantic domain under the COS, utilize Enhanced-AVLTree to make up corresponding service type packet node tree-model, lower floor utilizes resource issue that the Chord structure makes up the service of this classification and realizes, adopts the Enhanced-AVLTree structural network to guarantee in the situation that O(log n) navigate to fast the semantic classes category under the service; Utilize the mode of Enhanced-AVLTree and Chord combination to construct the balance that the P2P network is conducive to offered load, overcome the shortcoming of the load inequality of legacy network; The adding of Semantic Web is so that inquiry navigates to the advantages such as result more accurately.

Description of drawings

Fig. 1 is the network structure that the Enhanced-AVLTree that will construct among the present invention and Chord mix;

Fig. 2 is the flow chart that carries out the Semantic Web Services issue among the present invention at Fig. 1 network;

Fig. 3 is the semantic Web service finding flow chart that carries out at Fig. 1 network among the present invention;

Embodiment

The present invention is described further below in conjunction with the drawings and specific embodiments.

The present invention proposes technical scheme and mainly comprises two aspects: the one, and, will participate in the service discovery node and set up into corresponding network configuration (being called for short the service networking stage) by Enhanced-AVLTree and Chord; The 2nd,, in the network configuration that builds, carry out the service discovery (be called for short service discovery stage) of Semantic Web.

The corresponding characteristics that have equally the P2P network configuration based on Enhanced-AVLTree and the constructed hybrid P2P network of Chord, each node in the network both can be used as service register center and provided inquiry service for other nodes, the service that service requester uses other nodes to provide also is provided, and present network architecture can be served the publication and discovery operation at arbitrary node.The network configuration of constructing as shown in Figure 1, node in the network divides tree node and link point, each tree node belongs to again certain ring, the tree node of this ring is the bridge of linking up this ring group and whole network, if this tree node leaves or lost efficacy, the node in the ring is filled into for this reason tree node of ring successively thus.

The concrete steps in service networking stage are as follows:

(1) sets in the initial condition, the node set G of group acquiescence is arranged in the network ₀, the node of any not service issue all belongs to this group, and first node that adds this group becomes the tree node T of this group ₀, tree node T ₀Preserve the root node R of whole tree network ₀The address;

(2) for the node P of new adding network _i, at first it is joined node set G ₀, node P _iBy the following steps Web Services Publishing:

A) node P _iThe Web service w that at first wish is issued _iCorresponding semantic domain w _{I_}Category sends to the tree node T of this group ₀, tree node T ₀It is transmitted to root node R ₀

B) carry out the service type value key0 that Hash mapping obtains each tree node according to semantic domain, therefore can pass through computing semantic category w _{I_}The cryptographic Hash key0 of category _i, in network, find and semantic domain w according to the search rule of Enhanced-AVLTree tree _{I_}The semantic nearest tree node R of catogery _x

C) calculate tree node R _xCorresponding semantic domain R _{X_}Catogery and w _{I_}The semantic similarity Sim(R of catogery _{X_}Catogory, w _{I_}Catogory), if the similarity value, thinks then that both semantemes are similar greater than given threshold value, node P _iJoin tree node R as the link point _xAffiliated Chord ring is by corresponding Chord agreement, according to node P _iThe IP address computation go out respective nodes P _iCryptographic Hash to determine node P _iPosition in this Chord ring, and calculation services w _iThe corresponding service value of Query Information key1 _i, pass through key1 _iWith releasing news＜w of service _i, IP_w _iBe published to corresponding node P _xOn;

D) if step c) calculate semantic dissimilar, node P _iOneself become tree node R _i, set up new Chord ring G _i, R _iUnique identification in the Enhanced-AVLTree network is according to w _{I_}Catogory carries out Hash mapping and obtains, along with R _iAdding, the rule of the network based balanced tree of whole Enhanced-AVLTree is upgraded.

Because a node may issue different classes of service, determined but the Chord at its node place ring then is classification by the issuing service first time, and what preserve on the node is to serve w _iRelease news＜w _i, IP_w _i

During (3) for the new service of node issue that joins in certain ring, at first information on services is sent to the tree node of this node place ring, then issue according to a)-d) process;

By above-mentioned steps, can construct the P2P network of a mixed structure, this network is divided into two-layer, and the upper strata utilizes Enhanced-AVLTree to carry out organization and administration, and lower floor then utilizes the Chord agreement to manage.Semantic Web service finding process proposed by the invention is namely based on this P2P network, flow chart as shown in Figure 3,

Concrete steps are as follows:

(1) service requesting node is initiated service-seeking request query, through obtaining carrying out the query requests query_category of semantic matches after the semantic processes;

(2) query requests query_category is transmitted to the tree node Ri that the affiliated ring of node is sent in request, if query requests just comes from this tree node, then can omits this step;

(3) tree node R _iAfter receiving query requests query_category, will process query requests, concrete steps are as follows:

A) query_category is mated with the historical query buffer memory of this locality, if hit, then directly the result is returned to request forwarding person, otherwise enter next step.

The semantic similarity of the semantic domain that b) calculating query_category is corresponding with tree node, if semantic similar, then search the semantic similar Web service to query_category according to the Chord agreement in the ring under own, result queries is returned to the request promoter, upgrade simultaneously local historical query buffer memory, otherwise enter next step.

Query requests is transmitted to the meeting point the most similar to query requests query_category semanteme, according to the rule of Enhanced-AVLTree, query requests is transmitted to root node R ₀, the tree node R that then meets to semantic similarity according to the rule searching of binary search tree _x, then at R _xSearch the cryptographic Hash key1 of the corresponding inquiry service information of query_category according to the Chord agreement in the affiliated ring _q, find corresponding service and release news and send to inquiry and initiate node, if exceed the restriction jumping figure that sets in the ring, then inquire about unsuccessfully, return equally query failure message.

The Semantic Web Services modeling

(1) Web service service: Semantic Web Services is expressed as tlv triple s=(n, p, category), wherein:

A) n is service name;

B) P is expressed as the operational set that this service provides, and an operation can be expressed as two tuple p=(C ₁, C _o), C wherein ₁For operating the corresponding semantic concept set of all input objects, C _oBe the corresponding semantic concept set of all object outputs;

C) category represents the semantic domain that this service is affiliated, is a kind of semantic concept.

(2) semantic similarity: given semantic concept c ₁, c ₂, semantic similarity between the two is:

$\mathrm{Sim}(c_1,c_2)=\left\{\begin{array}{cc}{e}^{-\mathrm{\αl}}\·\frac{s^{\mathrm{\βh}}-s^{-\mathrm{\βh}}}{s^{\mathrm{\βh}}+s^{-\mathrm{\βh}}}& \mathrm{if}(c_1\≠c_2)\\ 1& \mathrm{if}(c_1=c_2)\end{array}\right.$ Formula (1)

Wherein:

L represents c ₁, c ₂Between shortest path length,

H represents c ₁, c ₂The degree of depth of common ancestor in the semantic concept inheritance tree,

α, β represent to limit parameter, are used for limiting l, the contribution degree of h.

The computational methods of this semantic similarity are not that the present invention proposes first, but a kind of existing method.

In the present embodiment, this discover method is divided into two stages to the process of service discovery: service networking stage and service discovery stage.Wherein:

1, serving networking during the stage, all nodes that participate in need to be got up based on Enhanced-AVLTree and Chord agreement organizations, containing Web service more or less on each node, is the node that provides as service, also is the requesting node as service discovery.The advantage of Enhanced-AVLTree and Chord is to carry out maintenance management for the semantic domain management and utilization Enhanced-AVLTree of service type, node for certain semantic domain inside, carrying out networking by the Chord agreement safeguards, the two-tier network structure all is to need corresponding index value up and down, the upper strata utilizes the semantic classification of service type to calculate corresponding cryptographic Hash key0, in order to contribute at Enhanced-AVLTree and to safeguard, and each node has the address of pointing to root node among the Enhanced-AVLTree, (this also is the characteristics that tree is searched to be convenient to like this to begin to search the tree node at the service place of inquiring about accordingly from any tree node, need to be from root node), simultaneously improved like this AVLTree can well be applicable to such situation, and all can be at O(log n for the operation of tree node) complexity under finish.The network using Chord of lower floor agreement, structurized P2P can navigate to needed resource easily and fast, also reduced simultaneously the load risk of network, same each node is that the cryptographic Hash key1 by its IP address determines its position in the Chord ring, and the present invention utilizes the realization of SHA-1 hash function.Key0 is that the semantic domain by service type carries out the Hash operation and gets, each service stored indications key1 in Chord ring need to utilize the specific search of the classification semantic domain of this service and service to indicate jointly to carry out the Hash operation and gets, so that releasing news of will serving is published to certain node in the Chord ring, the content that releases news comprises＜w ₀, IP_w ₀(＜information on services w ₀, the IP address of service place node 〉).

The content that mainly comprises following four aspects for the management of the constructed network of the present invention: node adds, and node leaves, service issue, oos service.

Node adds: a new node P _iThen add first acquiescence node set G when just having added in this network ₀, when this node is issued first service w ₀The time, make this node join service w according to the rule of top service networking ₀In the Chord ring of affiliated service type, or become new tree node, delete simultaneously G ₀In Maintenance Point T ₀In about node P _iInformation.To serve w simultaneously ₀Service be published to this Chord and encircle on the corresponding link point.

Node leaves: if a node P _iIf deviated from network is P _iBe a certain link point, then the tree node to the place ring sends request, and then the node according to the Chord agreement leaves the renewal adjustment that rule is carried out whole ring, P _iThe service of being responsible for releases news and need to dump to corresponding link point in this ring.If P _iBe the tree node of a certain link point, then need successively order from ring, to select the alternative P of a link point _iBecome new link point; If P _iBe the root node of tree network, then need simultaneously new root node (P namely _i) the address send to each tree node

Service issue: the flow chart of node issuing service as shown in Figure 2, detailed process is as follows:

1. node P _iThe Web service w that at first wish is issued _iCorresponding semantic domain w _{I_}The tree node R of ring under catogory sends to _iIf, P _iItself be exactly tree node, then omit this step;

2.R _iCalculate SHA-1(w _{I_}Catogory) value obtains w _{I_}The key0 value of catogory in the Enhanced-AVLTree network, R _iThe address of pointing to root node by the utilization of this value begins to search and w from root node _{I_}The tree node R that the catogory semanteme is the most similar _x;

3. calculate R _xCorresponding semantic domain R _{X_}Catogory and w _{I_}Semantic similarity Sim (the R of catogory _{X_}Catogory, w _{I_}Catogory), if the similarity value more than or equal to T _Sim, think that then both semantemes are similar, R _xCalculate SHA-1(w _i) value, obtain serving w _iRelease news at R _xKey assignments key1 in the affiliated ring, and will release news according to the Chord rale store to corresponding link point;

4. if what step 3 calculated is semantic dissimilar, then issuing service w _iNode P _iLeave original affiliated ring, become w _iThe tree node of the ring of affiliated service type, and be inserted in the Enhanced-AVLTree network on upper strata.

Cancel service: if node P _iNeed to cancel a certain service w of its issue _i, node P _iThe request of cancelling is transmitted successively according to the process of service issue, finally find the node location of serving the place that releases news, the corresponding service of deletion releases news.

2, in the service discovery stage, after the user sends query requests, the rule of the network that creates according to the present invention, identical with the flow process of service issue, transmit successively query requests, return all service results that satisfy request.

Concrete steps are as follows:

1. from P _iSend query requests query _x, P _iThe tree node R of place ring _i, R _iBy semantic processes with query _xConvert semantic query query to _x_ category also calculates corresponding cryptographic Hash (query _x_ category), by being searched for, tree finds the nearest tree node R of semantic similarity _x, enter step 2, otherwise search unsuccessfully

2. query requests query _xSend to R _x, calculate the cryptographic Hash (query of inquiry service _x) key1 _q, according to the Chord agreement at R _xPass through key1 in the affiliated ring _qFind and preserve the node that respective service releases news, and return corresponding Query Result; If the jumping figure in ring exceeds limit value, then do not inquire the result.

The above only is preferred implementation of the present invention; should be pointed out that for those skilled in the art, without departing from the inventive concept of the premise; can also make some improvements and modifications, these improvements and modifications also should be considered as in the protection range of the present invention.

Claims (1)

1. the Web service discover method based on balanced binary tree Chord network configuration is characterized in that, comprises service networking process and service discovery process;

Described service networking process comprises the steps:

11) set initial condition, the node set G of group acquiescence is arranged in the network ₀, the node of any not service issue all belongs to this group, and first node that adds this group becomes the tree node T of this group ₀, described tree node T ₀Preserve the root node R of whole tree network ₀The address;

12) for the node P of new adding network _i, at first it is joined node set G ₀, described node P _iBy the following steps Web Services Publishing:

121) node P _iThe Web service w that at first wish is issued _iCorresponding semantic domain w _{I_}Category sends to the tree node T of this group ₀, tree node T ₀It is transmitted to root node R ₀

122) carry out the service type value key0 that Hash mapping obtains each tree node according to semantic domain, namely by computing semantic category w _{I_}The cryptographic Hash key0 of category _i, in network, find and semantic domain w according to the search rule of Enhanced-AVLTree tree _{I_}The semantic nearest tree node R of catogery _x

123) calculate tree node R _xCorresponding semantic domain R _{X_}Catogery and w _{I_}Semantic similarity Sim (the R of catogery _{X_}Catogory, w _{I_}Catogory), if the similarity value, thinks then that both semantemes are similar greater than given threshold value, node P _iJoin tree node R as the link point _xAffiliated Chord ring is by corresponding Chord agreement, according to node P _iThe IP address computation go out respective nodes P _iCryptographic Hash to determine node P _iPosition in this Chord ring, and calculation services w _iThe corresponding service value of Query Information key1 _i, pass through key1 _iWith releasing news＜w of service _i, IP_w _iBe published to corresponding node P _xOn;

124) if step 123) calculate semantic dissimilar, node P _iOneself become tree node R _i, set up new Chord ring G _i, node R _iUnique identification in Enhanced-AVLTree tree network is according to semantic domain w _{I_}Catogory carries out Hash mapping and obtains, along with node R _iAdding, the rule of the network based balanced tree of whole Enhanced-AVLTree is upgraded;

During 13) for the new service of node issue that joins in certain ring, at first information on services is sent to the tree node of this node place ring, then according to step 121) ~ 124) issue;

Described service discovery process comprises the steps:

14) service requesting node is initiated service-seeking request query, through obtaining carrying out the query requests query_category of semantic matches after the semantic processes;

15) query requests query_category is transmitted to the tree node Ri that the affiliated ring of node is sent in request, if query requests just comes from this tree node, then can omits this step;

16) tree node R _iAfter receiving query requests query_category, will process query requests, concrete steps are as follows:

161) query requests query_category is mated with the historical query buffer memory of this locality, if hit, then directly the result is returned to request forwarding person, otherwise enter step 162);

The semantic similarity of the semantic domain that 162) calculating query requests query_category is corresponding with tree node, if semantic similar, then search the semantic similar Web service to query requests query_category according to the Chord agreement in the ring under own, result queries is returned to the request promoter, upgrade simultaneously local historical query buffer memory, otherwise enter step 163);

163) query requests query_category is transmitted to the meeting point the most similar to query requests query_category semanteme, according to the rule of Enhanced-AVLTree, query requests query_category is transmitted to root node R ₀, the tree node R that then meets to semantic similarity according to the rule searching of binary search tree _x, then at tree node R _xSearch the cryptographic Hash key1 of the corresponding inquiry service information of query requests query_category according to the Chord agreement in the affiliated ring _q, find corresponding service and release news and send to inquiry and initiate node, if exceed the restriction jumping figure that sets in the ring, then inquire about unsuccessfully, return equally query failure message.

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